Integrable Optics Test Accelerator Sergei Nagaitsev Fermilab April 3 , 2013

1. Integrable Optics Test AcceleratorSergei NagaitsevFermilabApril 3, 2013

2. Background and History • The Facility was motivated by the goal of building, testing and operating a complete ILC RF unit to: • Develop and demonstrate industrial and laboratory capability for producing state-of-the-art SCL components, assemble into a fully functioning system (photo-injector, bunch compressor, three 1.3 GHz ILC CMs, beamlines to dumps) • To carry out full beam-based system tests with high-gradient cryomodules and demonstrate ILC beam quality • It was recognized early in the planning process that an electron beam meeting the ILC performance parameters was itself a power resource of interest to the wider Advanced Accelerator R&D (AARD) community • In 2006, Fermilab was asked to lead the US ILC/SRF R&D Program • we felt that the most effective way to do that was to learn by doing • Construction of Test Facility began in 2006 as part of ILC/SRF R&D and later American Recovery and Reinvestment Act (ARRA) S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

3. Background and History • In planning the construction we therefore wanted to ensure that the facility offered something of enduring value when it was completed. • Hence, the investment in establishing a flexible facility that would readily support an AARD user program. • For those reasons the ARRA-funded facility construction incorporated space for • additional ILC cryomodules to increase the beam energy to 1.5 GeV, • space for multiple high-energy beamlines, • space for a small circular ring for the exploration of advanced concepts, • capability of transporting laser light into and out of the accelerator enclosure, • an adequately-sized control room • To date, an investment of $74M has been made, including $18M of ARRA funding, representing ~80% completion of the facility • In June 2012, anticipating the completion of the ILC R&D Program, Fermilab was directed to prepare a proposal for the AARD program. • Proposal submitted to the DOE in Feb 2013 S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

4. http://apc.fnal.gov/programs2/ASTA_TEMP/index.shtml S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013 Our Proposal

5. We proposed to establish a proposal-driven Accelerator R&D User Facility at Fermilab’s Advanced Superconducting Test Accelerator (ASTA) To do that requires: • Supporting the completion of ASTA in a phased approach: • Build out the linear accelerator to ~800 MeV with three Cryomodules • associated beam transport lines, dumps and support systems • Construct the Integrable Optics Test Accelerator (IOTA) • A small, flexible storage ring to investigate beam dynamics of importance to intensity frontier rings • In further phases • Add proton capability to IOTA (by reusing existing HINS equipment) • Increase peak current of compressed electron bunches by installation of 3.9 GHz system • Supporting the Operation of an Accelerator R&D User Program • Support staff required to operate a 9 month/year proposal-driven Accelerator R&D program S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

6. Substantial Investments Have Already Been Made At ASTA Beam Dumps: $2M Magnets and Power Supplies: $4M RF Power Systems: $8M S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013 Cryomodules: $15M Tunnel extension: $4.5M

7. New Muon Lab – home of ASTA, CMTF – home of PXIE New Muon Lab CMTF S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

8. Facilities S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

9. ASTA : Schematically (at the end of Stage IV) S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

10. ASTA : Upstream part 42‘ (13 m) 242‘ (74 m) Shows 3 SCRF CMs (1st CM – at Stage I.2, 2 more – Stage II) S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

11. ASTA : Downstream part 76‘ (23 m) 230‘ (70 m) proton RFQ not pictured (Stage III) S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

12. Experimental Areas 1 & 2 * 3.2nC × 3000 bunches × 5 Hz × 0.82 GeV = 40 kW S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

13. Experimental Area 3: IOTA S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

14. ASTA Science Thrusts S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

15. Intensity Frontier • Proposal: Experimental demonstration of integrable optics lattice at IOTA • FNAL, SNS, JINR, Budker INP, BNL, JAI, U. of Colorado, U. of Chicago • Proposal: Space Charge Compensation in High Intensity Circular Accelerators • FNAL, support from CERN, BNL • Experiments require the IOTA Ring • Difficult to implement needed linear optics in existing facilities • Lack of ring facilities in the US S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

16. A roadmap for high-intensity rings Being addressed now Addressed by ASTA • Increase dynamic aperture of rings with strong sextupoles and octupoles • Single particle dynamics • Also, addressed by the light-source community • Develop the theoretical basis of beam instabilities with strong space charge • Develop highly-nonlinear focusing lattices with reduced chaos • Reduce chaos in beam-beam effects • Ultimately, develop accelerators for super-high beam intensity • Self-consistent or compensated space-charge • Strong non-linearity (for Landau damping) to suppress instabilities • Stable particle motion at large amplitudes S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

17. Integrable Optics at IOTA S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013 • Main goals for studies with a pencil electron beam: • Demonstrate a large tune spread of ~1 (with 4 lenses) without degradation of dynamic aperture ( minimum 0.25 ) • Quantify effects of a non-ideal lens and develop a practical lens (m- or e-lens)

18. ASTA : Downstream part (now) IOTA S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013 beam dump

19. Integrable Optics: Motivation • Stability depends on initial conditions • Regular trajectories for small amplitudes • Resonant islands (for larger amplitudes) • Chaos and loss of stability (for large amplitudes) S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013 • The main feature of all present accelerators – linear focusing lattice: particles have nearly identical betatron frequencies (tunes) by design. • Hamiltonian has explicit time dependence • All nonlinearities (both magnet imperfections and specially introduced) are perturbations and make single particle motion unstable (non-integrable) due to resonant conditions

20. Does Focusing Need to be Linear? S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013 • Are there “magic” nonlinearities with zero resonance strength? • The answer is – yes (we call them “integrable”) • Search for a lattice design that is strongly nonlinear yet stable • Orlov (1963) -- attempt failed (non-integrable) • McMillan (1967) – first successfull 1-D example • Perevedentsev, Danilov (1990 - 1995) – several 1D, 2D examples • Cary and colleagues (1994) – approximate integrability • Our goal (with IOTA) is to create practical nonlinear accelerator focusing systems with a large frequency spread and stable particle motion. • Danilov, Nagaitsev, Phys. Rev. ST Accel. Beams 13, 084002 (2010)

21. Nonlinear Lenses S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013 • “Integrable Optics” solutions: • Make motion regular, limited and long-term stable (usually involves additional “integrals of motion”) • Can be Laplacian (with special magnets, no extra charge density involved) • Or non-Laplacian (with externally created charge –e.g. special e-lens or beam-beam E(r) ~r/(1+r^2) • Both types will be tested in IOTA

22. Concept: 2-m long nonlinear magnet S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

23. A single nonlinear lens FMA, fractional tunes 1.0 Large amplitudes νy Small amplitudes (0.91, 0.59) 0.5 0.5 νx 1.0 S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013 A single 2-m long nonlinear lens creates a tune spread of ~0.25.

24. Space Charge Effects in Linear Optics Lattice dQ_sc ~ 0.7 Tech-X simulations System: linear FOFO; 100 A; linear KV w/ mismatch Result: quickly drives test-particles into the halo 500 passes; beam core (red contours) is mismatched; halo (blue dots) has 100x lower density S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

25. Integrable Optics Lattice with Space Charge dQ_sc ~ 0.7 Tech-X simulations System: octupoles; 100 A; generalized KV w/ mismatch Result: nonlinear decoherence suppresses halo 500 passes; beam core (red contours) is mismatched; halo (blue dots) has 100x lower density S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

26. Space Charge Compensation Bringing Protons to IOTA 2.5 MeV RFQ HINS • Allows tests of Integrable Optics with protons and realistic Space-Charge beam dynamics studies • Allows Space-charge compensation experiments S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

27. Space Charge Forces & Compensation Z, beam direction B=E r, across the beam S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

28. Space-Charge Compensation in Circular Accelerators Goal: Experimental demonstration of the space-charge compensation technique with electron columns/electron lenses at dQ_sc >1 Why ASTA: Need 2.5 MeV high-current protons and IOTA – flexible lattice storage ring Relevant accelerators: All current and future high intensity proton rings (Booster, MI, all LHC injectors, MC rings, etc) S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013

29. Summary • ASTA offers: • A broad range in beam energies (50-800 MeV) • High-repetition rate and the highest power beams available • High beam quality and beam stability • The brightest beams available • Advanced phase-space manipulations (FB, EEX) • Linacs and ring (IOTA), electrons and protons, lasers • IOTAscientific goals are well aligned with Fermilabgoals and investments in Intensity and Energy Frontiers • ASTA is a great opportunity for collaboration, for post-docs and graduate students S. Nagaitsev, PASI 2nd annual meeting, Apr. 3-5, 2013